1. Field of the Invention
The invention relates to inspection of optical fiber connectors and more particularly to an adapter for fitting an MT ferrule assembly into a standard MPO connector receptacle so that the MT ferrule assembly may be inspected by conventional connector inspectors for MPO connectors.
2. Description of the Related Art
Within an optical fiber connector, a ferrule is used to provide a mechanical entity for holding the fibers in a desired position. The fibers will be fixed in the precision holes on the ferrule. The ends of the fibers fixed in the holes will be polished together with the end of ferrule, in order that the fibers will be mated perfectly with another set of fibers. An MT ferrule is a ferrule with multi-holes to provide multi-fibers to be connected. The MT ferrule is an essential part of the MPO (Multi-fiber Push On) or MTP (Mechanical Transfer Push-on) connector and other industrial fiber connectors. Alternatively, an MT ferrule may also be mated directly with another MT ferrule.
The structure of an MT ferrule assembled with optical fibers (namely an “MT ferrule assembly”) is shown in FIG. 1. As illustrated, an MT ferrule assembly 60 includes an MT ferrule 601 and a fiber array 602 wrapped in a protective cover 604. One end of the fiber array 602 is embedded in and extends through the MT ferrule 601 to be exposed on the front surface 614 of the MT ferrule 601. Thus, the endfaces 603 of the fibers in the fiber array 602 will be inspected from the front surface 614 of the MT ferrule 601. As an illustrative example, the fiber array 602 shown in FIG. 1 has two rows of fibers, each with 12 fibers. In actual practice, however, MT ferrules with one, two, four, or six rows of up to 12 fibers have been used. The MT ferrule 601 typically includes a front portion 610 and a rear portion 620. Both the front portion 610 and the rear portion 620 of the MT ferrule 601 have a rectangular cuboid shape. The front portion 610 has a relatively smaller cross section than the rear portion 620; more specifically, the rear portion 620 is wider and thicker than the front portion 610, and at the plane on which the front portion 610 meets the rear portion 620, the front portion 610 is symmetrically surrounded by the rear portion 620.
Before the MT ferrule assembly is further assembled into a standard MPO connector, or MT ferrule assembly is used as a stand-alone fiber connector, the ferrule endface (including the fiber endfaces) must be inspected to check if there are any defects, contamination, or even geometric inaccuracy. Any defects in the endface of the MT ferrule assembly have to be corrected beforehand. Otherwise, when the MT ferrule assembly 60 is directly mated with another MT ferrule assembly, the connection will not be satisfactory; if the MT ferrule assembly is embedded in an MPO connector housing, the MPO connector along with the embedded MT ferrule assembly has to be reworked or discarded. Therefore, it is important to inspect the MT ferrule assembly whether it is further assembled into an MPO connector or it is used alone.
Many apparatuses have been designed for inspecting optical fiber connectors. Two connector inspectors for inspecting MPO connectors are shown in FIG. 2 and FIG. 3.
FIG. 2 shows the alignment of an MPO connector 40 with an MPO connector adapter 30, an MPO inspector tip 20 (for 2-dimensional MPO connectors) and a microscope probe 10 to illustrate how an MPO connector 40 is interfaced with and inspected by the microscope probe 10 in the prior art. The MPO inspector tip 20 is disclosed by Zhou et al in the U.S. Pub. 2014/0063598. For the present application, it suffices to mention that the MPO inspector tip 20 has a front end 210 for connecting to the MPO connector adapter 30 and a rear end 211 for connecting to the microscope probe 10. The MPO connector adapter 30 has a front receptacle 301 and a rear receptacle 302. The front receptacle 301 is configured for receiving and positioning the front end 410 of the MPO connector 40, and the rear receptacle 302 is configured for receiving and positioning the front end 210 of the MPO inspector tip 20. When the MPO connector 40 and the MPO inspector tip 20 are both connected to the MPO connector adapter 30, and the rear end 211 of the MPO inspector tip 20 is connected to the microscope probe 10, the endface 414 of the MT ferrule embedded in the MPO connector 40 is properly positioned for inspection by the microscope probe 10.
Alternatively, an MPO connector may be inspected by an automated inspection system 50, such as the one disclosed by Zhou et al in the U.S. Pat. No. 8,988,670 and implemented with improvements as the LIGHTEL ARRAYVIEW system, as shown in FIG. 3. In brief, the automated inspection system 50 has an MPO connector holder 51 for holding an MPO connector receptacle 510 configured like the front receptacle 301 of the MPO connector adapter 30 (shown in FIG. 2). An inspecting microscope (not shown) is housed inside the automated inspection system 50 and the optical window 52 of the inspecting microscope is spaced from the MPO connector holder 51 for facilitating simultaneous cleaning of the endface 414 of the MPO connector 40 connected to the MPO connector receptacle 510.
It is economical to use an MPO connector's inspector to inspect MT ferrule assembly. However, the connector receptacle of conventional MPO connector inspectors such as the ones shown in FIG. 2 and FIG. 3 cannot fit with an MT ferrule assembly 60 directly.
It is the objective of the present invention to provide an adapter (namely, MT ferrule adapter) to quickly adapt the MT fiber assembly 60 into an MPO connector-type structure so that the MT fiber assembly 60 may be interfaced with a standard MPO connector adapter 30 or to an MPO connector receptacle 510 for endface inspection by conventional connector inspectors capable of inspecting MPO connectors.